King's Highway 401 also known as the four-oh-one is 816.6 kilometers (507.4 mi) long and stretching from Windsor through Toronto to the Quebec border.

The posted speed limit is 100 km/h (62 mph) throughout its length.

Highway 401 begins at Huron Church Road in Windsor. The section of Highway 401 from Windsor to London (especially west of Tilbury) has the nickname Carnage Alley and is known for deadly car accidents and pile-ups. This section is always overloaded with police cars.

Highway 401 widens to a total of 18 lanes south of Toronto Pearson International Airport but still is often congested in this section.

Highway 401 features about 19 service centers witch were completely rebuild and reopened in 2010-2011.